Propellant powder



Patented May 10, 1927. iv

UNITED STATES PATENT OFFICE.

JOHN M. OLIN AND ARTHUR S. ONEIL, OF ALTON, ILLINOIS, ASSIGNORS T0 WESTERN CARTRIDGE COMPANY, OF EAST ALTON, ILLINOIS, A CORPORATION OF DELAWARE.

PROPELLAN'I. POWDER.

No Drawing.

This invention relates to propellant powders, and more particularly to powders adapted for use in shot guns.

Slow burning powders, especially those having a nitro-carbohydrate base and progressive burning, are not adapted for use in shot guns, unless the loaded shot shell is especially designed. A dense nitrocellulose colloid burns progressively, that is, in layers until completely consumed. lVhile it is,

therefore, peculiarly adapted for rifle arms where the projectile seals the bore, it is not suitable for cylinder guns and small arms. In powders for cylinder guns, it is necessary that the initial burning be at a more rapid rate, due to the fact that the bore of the gun is not sealed by the projectile. Accordingly if the pressure is not rapidly developed, incomplete burning results, since the rapidity of burning depends directly upon pressure. Accordingly where a dense nitro-cellulose powder is employed in a cylinder gun, the result will be unburnt powder and escape of the gases around the wads, thereby reducing the ballistic eliiciency.

in the preparation of nitro-cellulose powder for use as military ammunition, it has further been the practice to subject the dense nitro-cellulose colloid to surface treatment by coating or impregnating the same with a suitable nitro-hydrocarbon, thereby producing a so-called progressive powder having a still lower initial pressure without, however, lowering the velocity of the projectile. The function of the solvent, however, is to act as a deterrent, as this solvent is not only less explosive and less readily ignitable than the dense intro-cellulose colloid, but it acts as a surface seal; it will,

therefore, be seen that this surface treatment goes still further in the opposite direction than the requirements and characteristics desired in a powder suitable for use in cylinder guns and small arms.

In order to produce a smokeless powder having a nitro-cellulose base, it has been the practice heretofore to either mix with the nitro-cellulose, metallic nitrates or a more violent explosive ingredient, such as nitroglycerin. The former, however, produces smoke, while both have a corrosive action on the bore of the gun; It has also been the practice to employ weak solvents so as to Application filed April 4, 1924. Serial No. 704,125.

only partially gelatinize the nitro-cellulose, or to employ ingredients with the nitro-cellulose while in a plastic state which are sub sequently extracted. These, however, are open to the objection that they do not provide stable and uniformly burning grains. It has also been proposed to incorporate with smokeless powder, either by mixing therewith or as a supplementary priming charge, black powder or to cause the black powder to adhere to the nitro-cellulose powder grains by a binder. These, however, are not only open to the objection that they introduce smoke forming and corrosive constituents, but the black powder is liable to segregate during shipment, thereby causing a given charge to be ununiform. This sifting or segregation is due to the fact that the densities and states of division of the powders vary.

One of the objects of this invention, therefore, is to provide a propellant powder mixture of slow burning and quick burning powders, but the densities of which are so close together as to prevent sifting and segregation of the powders.

Another object is to provide a powder mixture of colloided nitro-cellulose and black powders, in which a dense colloided intro-cellulose, and more particularly the surface thereof, is so modified as to modify its rate of burning and enable it to properly cooperate with the black powder in the mixture.

Further objects will appear from the detail description in which will be disclosed an embodiment of this invention.

In accordance with this invention the powder mixture consists generally stated of slow-binning and quick burning powders of substantially the same densities; and preferably also of substantially the same states of division. The slow-burning powder is preferably a nitrate of a carbohydrate, such as dense but modified colloided nitro-cellulose, while the quick burning powder is preferably black shot gun powder. The nitrate of a carbohydrate is preferably also so surface treated as to be progressive burning when fired in a shot gun.

The black powder may be of any suitable form and composition as is usual in black shot gun powders. The nitro-carbohydrate powder is, however, of special form since it must be of diiferent density than the ordinary dense colloided nitro-cellulose, but it should be of greater bulk but preferably rendered progressive burning.

A. nitro-carbohydrate powder which is adapted for mixing with black powder is that described in application Serial Number 618,388, filed February 10, 1923, since the density of that powder is substantially the same as that of black powder. That powder is a dense colloided intro-cellulose, in which, however, the grain is swollen to increase its bulk and this grain may then be impregnated with a deterrent to render it progressive burning. As described in application Serial Number 618,388, such a powder is prepared as follows:

A dense colloided nitro-cellulose powder is ground or cut up in any suitable apparatus to the state of division desired, and it is then screened to the desired size. This powder is then intimately mixed with a solid nitro-hydrocarbon, such as dinitro-toluene, in the proportion of ninetyeight (98) parts of the powder and two (2) parts of the solvent, although the proportions may be varied within limits to suit requirements. The mixture is then introduced into a tank provided with a stirring mechanism, or into a tumbling barrel, which tank or barrel has been previously filled with water and raised to a temperature of 7 5 to 100 (1., depending upon the nature of the solvent used. The temperature is maintained (by supplying l'ive steam or water to a jacket or by the direct action of steam) for a suitable period, in case where dinitro-toluene is used for a period of about two hours, while the powder and the solid solvent are rumbled together in the water. The solvent under the influence of heat melts and distributes itself uniformly ,over the grain. Now dinitro-toluene (as well as other solid nitro-hydrocarbon solvents) under the influence of heat is a solvent and a colloiding agent for nitro-cellulose. Accordingly the solvent penetrates the powder grain, the depth of penetration depending upon the period of heating, the quantity of the solvent, and the temperature of the heat applying vehicle. It is essential that the penetration take place rather rapidly otherwise little or no swelling of the grain takes place. It is also essential that the temperature be maintained until the desired penetration takes place.

The resulting grain then comprises a core of dense powder enclosed by an envelope of nitro-cellulose colloided with dinitro-toluene, which in common with such colloids occupies a greater volume and is less dense than the core or body of the grain. It is, however, necessary to fix this condition and in order to accomplish this, the solvent action is not only interrupted but the powder grain is chilled. When, therefore, the colloiding and swelling action has progressed as far as desired, cold water is admitted to the mixture in order to rather suddenly chill the contents of the tank or barrel. This causes the dinitro-toluene to chill, thereby partially recrystallizing and losing its solvent properties so that the solvent action is interrupted.

It will, of course, be understood that after chilling the treated grains are removed from the water and dried in. the usual manner. This drying will not, however, cause contraction of the envelope to the original colloid density, but this envelope will remain in a porous condition since the drying will rather enhance than detract from the porosity. The drying .can be accomplished in any suitable manner as usual in the art.

This bulked powder is now again subjected to the action of a deterrent so as to render the same progressive burning; this may be accomplished in any suitable manner as by rumbling it with about two percent of dinitro-toluene, at a temperature of about 80 for about one-half hour so that each grain will become impregnated with the treating agent.

The powder so produced may be mixed with black powder of substantially the same state of division and in the proportion of 10 to 15% of black powder and 90 to 85% modified dense colloided nitro-cellulose powder as described. Good results are obtained if the powders are subdivided sufliciently to pass a thirty mesh screen. It will be understood, however, that other quick burning powders and ingredients may be used to hasten the ignition.

There is thus produced a powder mixture in which sifting and segregation will be prevented, due to the fact that the component powders are of substantially the same densities and states of division. The black powder acts to supplement the primer in not only starting the ignition of the progressive powder, but also in maintaining the necessary pressure and temperature to effect that result. The progressive burning of the nitro-hydrocarbon powder, however, keeps up the pressure behind the shot charge until the latter leaves the gun.

lVhile in the specification and claims the term grain is used, it is to be understood that it is intended as a word of general description and not of limitation, but to include the various forms in which powder is produced for use. It will be further understood that while theories of formation and operation have been advanced, the invention is not necessarily limited thereto. It will further be obvious that various changes may be made in details without departing from the spirit of this invention; it is, therefore,

ill

to be understood that this invention is not to be limited to the specific details described.

Having thus described the invention, what is claimed is:

1. A propellant powder mixture of slowburning powder grains and quick-burning powder grains of substantially the same densities.

2. A propellant powder mixture of slowburning powder grains and quick-burning powder grains of substantially the same densities and states of division.

3. A propellant powder mixture of nitrocarbohydrate powder grains and black powder grains of substantially the same densities.

4. A propellantpowder mixture of colloided nitro-cellulose powder grains and black powder grains of substantially the same densities.

5. A propellant powder mixture of nitrocarbohydrate powder grains and quick burning powder grains, theintro-carbohydrate powder grains being swollen to approximate in density those of the quick burning powder.

6. A propellant powder mixture of nitrocarbohydrate powder grains and quick burning powder grains, the nitro-carbohydrate powder grains being swollen and surface treated to render them progressive burning.

7. A propellant powder mixture of slowburning powder grains and quick-burning powder grains, the slow-burning powder grain consisting of a dense core surrounded by a less dense envelope.

8. A propellant powder mixture of slowburning powder grains and quick-burning powder grains, the slow-burning powder grain consisting of a dense core surrounded by a less dense surface treated envelope toreuder it progressive burning.

9. A propellant powder mixture of nitrocellulose powder grains and black powder grains, the nitro-cellulose powder grain con sisting of a dense core surrounded by av less dense envelope.

10. A propellant powder mixture of nitrocellulose powder grains and black powder grains, the intro-cellulose powder grain consisting of a dense core surrounded by a less dense envelope containing a. deterrent.

11. A propellant powder mixture of black powder grains, and dense colloided nitrocellulose powder grains the surfaces of which are of less density than the cores thereof.

12. A propellant powder mixture of black powder grains, and dense colloided nitrocellulose powder grains the surfaces of which contain a deterrent and are of less density than the cores thereof.

13. A propellant powder mixture of black powder grains, and dense colloided nitrocellulose powder grains the surfaces of which are partially decolloided.

14:. A propellant powder mixture of black powder grains, and dense colloided nitrocellulose powder grains the surfaces of which are partially decolloided and contain a deterrent.

In testimony whereof we aflix our signatures this 24th day of March, 1924.

' JOHN M. OLIN.

ARTHUR S. ONEIL. 

